[Solved] QML Back Button with JavaScript or ListModel?

kyleplattner

I tried implementing with JavaScript but I couldn't get it to work. Any ideas would be appreciated.

@ var count = 0;
var stack = [];
var lastpage;

function changePage(newPage)
{

    pageLoader.source = newPage;
    stack.push(newPage);
    count = count + 1;


}

function lastPage()
{

lastpage = stack.pop(count);

}
@

For my back button the code is:

@MouseArea {
id: mouse_area_back
x: 0
y: 381
width: 82
height: 99
onClicked: {
console.log(PageChange);
pageRequested(PageChange.lastpage);
}
}@

and my main page:

@import Qt 4.7
import "pageChanger.js" as PageChange

Rectangle {
width: 640
height: 480

function changePage(newPage) { PageChange.changePage(newPage) }

Loader {
    id: pageLoader
    z: 1
    source: "1.qml"
}

Connections {
    target: pageLoader.item
    onPageRequested: changePage(page)
}

}

@

xsacha

You're almost there (with the first one you had).
Don't worry about the javascript, you can do it in the QML (which really is javascript anyway).

The only thing you're missing is the page stack. Where is the page variable? And why is it a string? If you are putting the filename (eg. 1.qml) then you don't need the model.

kyleplattner

You will have to excuse my ignorance again but how do I implement a page stack in qml?

xsacha

Like you were trying to do in the javascript.
Make a List with previous pages you have accessed.

I don't think you are showing all the code? When you change page (purposefully), you need to append that page to the 'stack' -- your history (like the javascript code does).
Then, when you use the back button, simply change to the last item on your page stack. Then remove that item.

kyleplattner

I like the concept but I am weak on the qml code.

xsacha

I'm weak on interpreted code, more a C++ guy, but QML seems the same as Javascript (at least syntax-wise).

If you can provide me with a minimal code base that needs this 'back button' functionality, I can add it on for you. No need to give me all the pages, just two or three will do.

kyleplattner

These are my pages as they stand, javascript still there from attempt 1.

My Main.qml:

@import Qt 4.7
import "pageChanger.js" as PageChange

Rectangle {
width: 640
height: 480

function changePage(newPage) { PageChange.changePage(newPage) }

Loader {
    id: pageLoader
    z: 1
    source: "1.qml"
}

Connections {
    target: pageLoader.item
    onPageRequested: changePage(page)
}

}

@

PageChanger.js

@ var count = 0;
var stack = ["1.qml"];
var visited;

function changePage(newPage)
{

    pageLoader.source = newPage;
    stack.push(pageLoader.source);
    count = count + 1;
    console.log(count)

}

function lastPage()
{

console.log("in function")
console.log(stack);

// stack.pop();
stack.pop();
console.log(stack);
pageRequested(stack);

}
@

A Sample Page:

@import Qt 4.7

Rectangle {
id: screen
width: 640
height: 480
color: "#086421"
signal pageRequested(string page)

Rectangle {
    id: rectangle1
    x: 1
    y: 0
    width: 557
    height: 95
    gradient: Gradient {
        GradientStop {
            position: 0
            color: "#b36c67"
        }

        GradientStop {
            position: 0.21
            color: "#661d17"
        }
    }
    border.width: 0
    border.color: "#086421"


    MenuTitle {
        id: menutitle1
        x: 0
        y: 0
        title: "Screen Brightness"
    }
}

TabMenu {
    id: tabmenu1
    x: 0
    y: 48
    state: "State2"
    onPageRequested: screen.pageRequested(page)
}

SetupBars {
    id: setupbars1
    x: 558
    y: 0
}

}

@

Setup Bars code:

@import Qt 4.7
import "pageChanger.js" as PageChange

Rectangle {
width: 82
height: 480

SetupBlack {
    id: setupblack1
    x: 1
    y: 383
}

SetupBlack {
    id: setupblack2
    x: 1
    y: 287
}

SetupBlack {
    id: setupblack3
    x: 1
    y: 191
}

SetupBlack {
    id: setupblack4
    x: 1
    y: 95
    smooth: true //test
}

SetupBlack {
    id: setupblack5
    x: 1
    y: -1
}

Text {
    id: text1
    x: 15
    y: 36
    width: 80
    height: 20
    color: "#ffffff"
    text: "Home"
    font.pixelSize: 19
    font.family: "Arial"
    font.bold: true
}

Image {
    id: image1
    x: 5
    y: 395
    width: 73
    height: 50
    source: "Images/back.png"
}

Text {
    id: text2
    x: 18
    y: 440
    width: 80
    height: 20
    color: "#ffffff"
    text: "Back"
    font.bold: true
    font.family: "Arial"
    font.pixelSize: 19
}

MouseArea {
    id: mouse_area1
    x: 0
    y: -2
    width: 82
    height: 97
    onClicked: pageRequested("1.qml")
}

MouseArea {
    id: mouse_area_back
    x: 0
    y: 381
    width: 82
    height: 99
    onClicked: PageChange.lastPage();
    }

}
@

xsacha

One of the more important parts is 'TabMenu'. I guess it has all the pages on it?
I will try to implement some buttons there.

kyleplattner

I really had to cut that up to get it to fit within the 6000 character limit but hopefully the bulk of what matters is there.

xsacha

It's alright, I don't need the TabMenu. I just made some buttons. So deleted that huge post :)

I have finished the back button. Here it is:

Main.qml
@iimport QtQuick 1.0
Rectangle {
width: 640; height: 480
ListModel {
id: pageModel
function pageRequested(page)
{
append({"page": pageLoader.source})
pageLoader.source = page
}
function pageLast()
{
pageLoader.source = get(count - 1).page
remove(count - 1)
}
}
Loader {
id: pageLoader
anchors.left: parent.left
source: "home.qml"
}
SetupBars {
anchors.right: parent.right
width: 80
}
}@

PageButton.qml
@import QtQuick 1.0

Rectangle {
property alias text: status.text
property string file
width: 100; height: 30
border.width: 3
border.color: "#086421"
Text { id: status; anchors.centerIn: parent }
MouseArea { anchors.fill: parent; onClicked: pageModel.pageRequested(file) }
}@

Home.qml
@import QtQuick 1.0

Rectangle {
id: screen
width: 560; height: 480
color: "#A834F1"
Text {
text: "Welcome Home!"
anchors.centerIn: parent
}
Rectangle {
id: rectangle1
width: parent.width
height: 95
gradient: Gradient {
GradientStop { position: 0; color: "#b36c67" }
GradientStop { position: 0.21; color: "#661d17" }
}
PageButton {
x: 50; y: 50
text: "Bluetooth"
file: "1.qml"
}
PageButton {
x: 200; y: 50
text: "Screen Brightness"
file: "2.qml"
}
}
}@

1.qml
@import QtQuick 1.0

Rectangle {
id: screen
width: 560; height: 480
color: "#086421"
Text {
text: "Bluetooth!"
anchors.centerIn: parent
}
Rectangle {
id: rectangle1
width: parent.width
height: 95
gradient: Gradient {
GradientStop { position: 0; color: "#b36c67" }
GradientStop { position: 0.21; color: "#661d17" }
}
PageButton {
x: 50; y: 50
text: "Screen Brightness"
file: "2.qml"
}
}
}@

2.qml
@import QtQuick 1.0

Rectangle {
id: screen
width: 560; height: 480
color: "#9864F1"
Text {
text: "Screen Brightness"
anchors.centerIn: parent
}
Rectangle {
id: rectangle1
width: parent.width
height: 95
gradient: Gradient {
GradientStop { position: 0; color: "#b36c67" }
GradientStop { position: 0.21; color: "#661d17" }
}
PageButton {
x: 50; y: 50
text: "Bluetooth"
file: "1.qml"
}
}
}@

SetupBars.qml
@import QtQuick 1.0

Rectangle {
id: screen
width: 80; height: 480
color: "black"
Text {
id: text1
x: 15; y: 36
width: 80; height: 20
color: "white"
text: "Home"
font.pixelSize: 19
font.family: "Arial"
font.bold: true
MouseArea {
anchors.fill: parent
onClicked: pageModel.pageRequested("home.qml")
}
}
Item {
anchors.bottom: parent.bottom;
width: 80; height: 50
visible: pageModel.count > 0
Image {
anchors.left: parent.left
source: "Images/back.png"
}
Text {
anchors.right: parent.right
color: "white"
text: "Back"
font.bold: true
font.family: "Arial"
font.pixelSize: 19
}
MouseArea {
anchors.fill: parent
onClicked: pageModel.pageLast();
}
}
}@

kyleplattner

Thanks so much for your help.

kyleplattner

Just a note: I got it to work only when I put "pageLoader.source = get(count - 2).page" and not "pageLoader.source = get(count - 1).page"

xsacha

You must have added something to the list.
As count is indexed starting with 1 while the array is indexed starting with 0, you use count-1 to map to the array. Hence, count-1 retrieves the last element in the array. Your version will get the second last element in the array, so something odd there.

The one I posted works perfectly though (without adding any additional code) :)